This invention relates to material processing equipment and, more particularly, to apparatus for removing tramp metal from material to be processed.
Historically, a major problem with material crushing equipment, whether the equipment be roll-type crushers or cage-type impact crushers, is the presence of tramp material such as tramp iron in the material, typically a mineral such as coal which is being crushed. In a cage-type impact crushing mill, for example, the cages rotate in opposite directions typically at speeds of between 500 and 1000 revolutions per minute (rpm). The feeding of tramp iron between the counter-rotating cages can severely damage the mill resulting in expensive equipment repair and extensive down-time.
Various methods have been employed to try to remove tramp metal including diversion gates such as shown in U.S. Pat. No. 4,480,753 and various types of metal detectors. Metal detectors are often aggravating to operate because the detection of tramp metal usually stops material feed until the tramp metal is located and either removed or tagged for later removal. Only after this is done is feeding restarted. Since tramp metal may be detected numerous times during the course of an operation, the repeated shut downs add to the cost of the crushing operation and become a nuisance. What is required is a removal system which is automatic, so that the operator does not have to locate pieces of tramp metal; effective to remove all tramp metal; yet simple in operation.
This tramp removal apparatus solves the above problems in a manner not revealed in the known prior art.